Truck pivot damping



May 12, 1936. KRUCKENBERG AL 2,040,262

TRUCK PIVOT DAMPING Filed Jan. 51, 1935 3 Sheets-Sheet l 9 fig- 40 37 as as 52 y 1936- F. KRUCKENBERG AL 2,040,262

TRUCK PIVOT DAMPING Filed Jan. 31, 1955 3 Sheets-Sheet 2 a2 34 30 33 24 57 55 54 Fig. 6 59.7

2 1 band? 65 as as 32 5530 659 67 @1 33 4 2 7 y 1936- F. KRUCKENBERG ET AL 2,040,262

I TRUCK PIVOT DAMPING Filed Jan. 31, 1953 s Sheets-Sheet H Fig. 11

12 (Jech'anH'Z IIIIIIIIIIIIIIIIIIIIII/IIIA II/IIIIlIIl/II/IIIIIIl/II, "I

Fig. 13

Patented May 12, 1936 UNITED STATES PATENT OFFICE TRUCK PIVOT DAMPING Application]: anuary 31, 1933, Serial No. 654,540

ermany February 10, 1932 Claims.

It is known that railway vehicles of short wheelbase, particularly the trucks of such vehicles, tend to vibrate laterally, that is the pairs of wheels, of whichthe flanges always have a certain play 5 in the track, for some reason during travel on straight sections commence to run with the flanges alternately against one rail and the other at more or less equal intervals. The vehicle body then swings on a vertical axis which is always found very uncomfortable by the passengers. Besides this the forces between the rails and flanges may become so high through resonance efi'ects that the running of the vehicle on the track becomes endangered. While in individual coaches of short wheel base these movements can occur unhindered, in trucks they are in general braked by the frictional forces arising between the bearing surfaces of the vehicle body and the truck. But these braking forces alone do not sufiice to produce steadiness at high speeds. It is necessary to make the truck wheel base very considerable to make the possible inclination to the rail direction small. But from another point of view this increase oi. wheel base is undesirable with high speeds, for it always means an increase in weight. Moreover the provision of a low coach floor which is very desirable in a high speed coach, is hindered because long trucks would reduce the useful space to an unpermissible extent. In addition, frictional damping is in its nature unsuitable because in the braking of turning movements of a truck with respect to the vehicle body by friction, jolts occur through the sudden changes from the coefiicient of friction at rest to the coefiicient of friction in. motion which may be uncomfortable at high speeds and with light coach bodies.

These disadvantages are avoided when the truck is provided according to the invention, with suitable liquid damping which brakes the turning movements. bration is thereby made impossible even when a short wheel base is used. Liquid damping has the 45 particularly desirable characteristic that the damping force depends on the speed of movement. Slow turning movements, which are quite harmless are but little damped, while rapid turning movements produced by shocks are damped all 50 the more strongly.

The invention will be more particularly described with reference to the accompanying drawings, in which:

Fig. 1 is a vertical section and Fig. 2 is a plan 55 view of one embodiment of the invention;

The occurrence of pivotal vi-' Fig. 3 is an enlarged detail of a portion of the structure of Fig. 2;

Fig. 4 is a section on line III-I11 of Fig. 3;

Fig. 5 is a detail of a modification of the invention;

Fig. 6 is a side view and Fig. '7 is a transverse section of a further modification of the invention;

8 is a transverse section and Fig. 9 is a plan view of another modification of the invention; 10

Fig. 10 is a plan view of a further modification of the invention;

tail of a further modification of the invention.

Figure 1 (vertical mid section) and Figure 2 (plan view) of the accompanying drawings show 20 a simple arrangement of the kind just mentioned. The vehicle body 2| rests with the sliding surfaces 22 and 23 on the truck frame 24 which carries a fixed bearing 25 for the pivot 26 secured to thebody 2|. On the truck frame 24 is also se- 25 cured a cylinder 21 filled with a braking liquid, in which works a piston 28. The piston rod 30 passing through a stufiing box 29 is connected to the body 2' l by a link 3!. When the truck is parallel with the longitudinal axis of the vehicle the 30 piston 28 is in mid position, whereby the cylinder 21 shown again on enlarged scale, in Figure 3 (vertical mid section) and Figure 4 (cross section on III-411), is divided into two equal chambers 32 and 33. The cylinder ends are connected by a 35 conduit 34 in which is a throttle valve 35. As will be seen from Figure 2 the piston moves a certain distance in the cylinder when the truck pivots with respect to the body, whereby liquid pressed on by the piston is forced in known rhan- 40 ner from one side of the piston through the conduit 34 and valve 35 to the other side. The degree of damping depends on the size of passage to which the valve .35 is adjusted. With very violent lateral shocks between the truck and track,

which result in very rapid pivoting of the truck. the pressure in the cylinder might rise so much as to stress the parts of the damping apparatus to an excessive degree. In this event, for example with very rapid movement of the piston 'between them the flange 49 on the rod 4|.

end of the cylinder a corresponding quantity of liquid must be able to enter the cylinder end 33 from the chamber 31, which takes place through automatic opening of the very lightly spring loaded suction valve 38. If the piston moves very rapidly towards 33, the corresponding valves 39 and 40 act to limit the pressure.

Limitation of pressure can also be achieved without valves, by the provision of a yielding member at a suitable place in the external damping gear. -Figure 5 (vertical mid section) shows an example. The link 3| pivoted at one end of the piston rod 30 is pivoted at its other end to a rod 4|. This rod slides in bearings 42 and 43 secured to the body 2| and serving as abutments for preloaded springs 44 and 45. The spring collars 46 and 41 bear against the abutments 48 secured to the body 2| and at the same time firmly grip If new during a particularly rapid swing of the truck the liquid pressure exceeds a determined value corresponding with the preloading of the respective spring 44 or 45, the latter, for example with motion in the direction of the arrow 56 the spring, is compressed, the collar 46 being moved away from the abutment 48 by the flange 49 of the rod 4|. The spring 45 remains in position unafiected. In this way the greatest forces in the damping gear are determined by the characteristics of the springs 44 or 45 which can be chosen as desired.

It must also be borne in mind that damping is only desired during the swingingfirst described herein, of the truck on straight sections. For the much greater displacements during travel on curves damping 'is unnecessary, as lateral vibrations do not here occur. Damping is indeed disadvantageous since it hinders the-easy movement of the truck into the necessary position for traverse of the curve. The damping device must accordingly be so arranged that with small movements of the piston from the mid position heavy damping takes place, while for larger movements slighter damping occurs. This is achieved by the grooves 5| and 52 provided in the cylinder wall. Accordingly the piston only makes joint with the cylinder wall over a short stroke corresponding with travel on a straight track while with larger piston movements the liquid can flow directly round the piston through the groove 5| or 52 from one cylinder and to the other whereby damping is almost completely suppressed. The same efiect can be obtained by the throttle valve 35 being suitably connected to the damping gear so that with increased pivoting of the truck a larger passage for the liquid is automatically provided.

The above described arrangements of the liquid damping apply to a particularly simple case in so far as the truck can only pivot with respect to the vehicle body. If lateral translatory movements also occur and such purely translatory movements are not to be damped, a different connection between the vehicle body and the damping device is necessary, for example as shown in Figure 6 (side view) and Figure 7 (cross section). The bearing 25 for the pivot 26 fixed to the body 2| is carried in guides 53 in the truck frame 24. Accordingly the truck can slide sideways as well as pivot beneath the body 2| supported on the sliding surface 22 and 23. The damping device is the same in principle as in Figures 1-4, but the cylinder spaces 32 and 33 are here formed as two separate, coaxial, opposed cylinders 32 and 93. The two damping pistons, of which only one 28 is seen in the cylinder 32 shown in section, are coupled by a rigid rod 36 but stufiing boxes to guide it can be omitted. The cylinders 32 and 33 are again connected by a conduit 34 with throttle valve 35 and exactly correspond in the other details and mode of operation, with the cylinder shown in Figures 3 and 4. The piston rod 30 has at its centre an eye 54 in which engages the cylindrical projection 55 of connecting member 56. The member 56 itself is rotatably borne in two eyes 51 and 58 secured to the body 2 l During purely lateral movements of the truck the member 56 simply swings on the axis 51-58, its projection 55 sliding in the eye 54 of the piston rod 36. Longitudinal movement of the piston rod 30 and the pistons with respect to the cylinder 32 and 33 and-accordingly a damping effect, only occurs, as will readily be seen, when the truck 24 pivots with respect to the body 2|.

The mountingof a damping device of the described kind upon a known construction of truck particularly suitable for high speed vehicles, is

mon piston rod 30, secured to the side of the truck frame 26. It is here merely necessary to provide the cross beam 59 with an extension 61 projecting over the side member of the truck frame and connected with the piston rod 36 by a guided block device 68. It will readily be seen that the damping device does not act when the on it by rolling bodies 66. The actual damp- 5 ing device is,'exactly as in Figures 6 and 7, in the form of two cylinders 32 and 33 with a comtruck only moves laterally parallel with itself.

In indicating such a movement, in Figure 9, for the sake of simplicity, the body 2| has been assumed to have moved with respect to the truck, the points 65 and 65 taking the positions 66 and 65' respectively, the points 60, 6|, 66 and 65" no longer forming a rectangle but still a parallelogram. The cross beam 59 during such relative movement has made no movement with respect to the truck frame 24 and the damping device has therefore not been set in action. If however the frame 25 pivots about the pin 26, the cross beam and. its associated parts namely the extension 61 and piston rod 36 do not partake in this movement so that movement of the pistons in the cylinders 32 and 35 takes place and damping results as described above.

Figure 10 shows a truck of similar construction but the clamping device is mounted at the end of the frame 26. To the cross beam 59 an arm 69 is rigidly fixed, here longitudinal of the vehicle, which again will move with respect to the frame 24 if the latter pivots about the pin 26. The damping device III in this case is in the form of a rotary wing damper. of the kind known for example in motor vehicle construction. This .device is shown on a somewhat larger scale in Figure 11 (vertical mid section), Figure 13 (plan view) and Figure 12 (horizontal section on the line XI-XI). 'The casing 1| secured upon the frame 24 is closed top and bottom by covers 12 and 13 in the' centre of which the shaft 14 is borne. .A dividing wall i5 through which the Gal shaft H passes divides the interior of the casing into two chambers 18 and ll of which the lower the walls of the chamber I1 and divides it into two parts 18 and 80 (Figure 12).

As Figure 12 shows the chamber 11 is of sector form the angle of which, is governed by the greatest angular displacement of the wing 18. The spaces 18 and 80 are connected by a conduit 34 for the liquid, in whichthe throttle valve 85 is included. The shaft 14 further carries, at its upper end, an arm 8| in a slot 82 in which can slide a block 83. The arm 88 (see also Figure 10) engages with this block by a pin 84. If the longitudinal axis is exactly in the direction of the vehicle body, that is if the pivotal angle is zero, the arms 88 and 8| and the wing 18 are in line. Upon pivoting of the truck about the pin 26 (Figure 10) the arm 88 retains its position while the damping device is moved. The great length of the arm 68 compared with the arm length ll-84 is of great advantage. The small deviations of the truck are thus translated into much greater movements of the wing 18. The ratio changes with increasing deviations, in that the arm length IL-84 becomes longer. As Figure 13 shows the point 84 moves on an arc I about the centre of the truck pivot and at the maximum pivotal angle is at 84. The length |484 has increased slowly at first, but then faster to 14-84. For a given angular velocity of the truck, the angular velocity of the wing accordingly decreases with increase in deviation, and the damping effect becomes less. This characteristic, here obtained by simple means, is important for easy movement of the truck on curves, as explained earlier herein. Just as in the cylinder according to Figures 3 and 4, this effect can be increased by the provision of grooves 5| and 52 (Figure 12) which with large movements of the wing permit direct flow of the liquid from one side of the wing 18 to the other.

To limit the pressure in they case of very rapid movements, pressure relief and suction valves can be provided in the dividing wall between each of the parts I8 and 80, and the chamber 16, exactly corresponding with Figure 3. Limitation of the greatest damping force can also be effected without safety valves, for example by the arrangement shown in Figure 14. The somewhat shorter arm 88 here does not engage directly with the arm 8| (Figures 10 and 11) of the damping device but has an intermediate lever 88 pivoted to its end, which at one end is coupled, to the lever 8| of the damping device by the pin 84 and at the other end is provided with projections 81. Two lugs 88 and 88 arranged laterally of the arm 68 each have two eyes 80, 8| and 82, 83 respectively, shown in section, which serve as guides for pin 8|, 85, and as abutments for respective preloaded springs 86 and 81 and as stops for shoulders 88 and 88 on the pins 84 and 85. If now the truck and relatively thereto the point 85, makes a very rapid pivotal movement, the point 84 and therefore the damping device is not obliged to follow closely. The intermediate lever 86 can turn about the point 85 whereby one of the springs, for example 86, is compressed through the pin 84 and shoulder 88, while the other spring retains its position.

While in most cases it is desirable for technical reasons only to damp purely pivotal movements in trucks able also to make lateral translatory movements, as in the devices above described, it may sometimes be desirable to damp such translatory movements as well. The simplest way of doing this is by arranging the bars 62 and 63 in a truck arrangement according to Figures 9 and 10, so that they are not parallel, the length 686| of the cross beain 58 being made for example smaller than the distance between the points 64 and 65. It will be obvious that in this case a purely translatory lateral movement of the truck will cause a movement of the damping pistons, which will be all the more, the greater the difference between the lengths Gil-6| and 8465. The damping responds to pivotal movements just as before.

The preferred arrangements of the damping devicesin the examples described above are all shown for trains or vehicles in which each body has its own trucks. Multi-coach trains, for example those with self propelled coaches, are often constructed however with the adjacent ends of two relatively movable coach bodies supported on a common truck. If such a train travels mainly in one direction, the damping will be arranged so that it is brought into action by the leading coach body. Then upon running into a curve, first the leading coach body is turned into the curve direction by the leading truck and the body then begins to turn the following truck in the same direction through the damping device. This truck will therefore run into the curve very easily and entirely without shock. The damping can then be made very heavy, that is the throttle valves 35 Figures 3 and 12 in the conduit 34 can be wholly or almost wholly closed, which is necessary for steady travel on straight sections. If such a multi-coach train travels equally in both directions it is advantageous to provide the trucks with two damping devices, each of the coach bodies resting on the truck actuating one of them. The throttle valves of the two damping devices will then be set equally. To obtain the same action as in the above mentioned case of a train travelling mainly in one direction, the damping brought into action by the leading coach must always be made heavy and the other light or even put completely out of action, which can be effected say in conjunction with the driving control of the train.

We claim:

1. A damping mechanism for steadying the running of vehicle bogie trucks including a cross member pivotally mounted on the truck, a pair of substantially longitudinal link bars each pivotally connected at one end to either end of the cross member and at the other end to the vehicle body, a liquid braking device on the truck and a member rigidly attached to said cross member and operatively connecting it with said liquid braking device, whereby pivotal vibrations of the truck are damped.

2. A damping mechanism as defined in claim 1 wherein said member connecting the cross member and the liquid braking device includes a yielding member adapted to limit the maximum damping force.

3. A damping mechanism as defined in claim 1 wherein the liquid braking device is a rotary wing damper and the member connecting the said cross member therewith is an arm coupled to an arm on the damper wing shaft by a block and slot connection.

4. In a high speed rail car including a car body and bogie trucks supporting said car body 40 and mounted to swivel pivotally upon va, center pin and toswlng laterally relative to saidcar body, mechanism for damping the pivotal vibrations of the truck comprising a liquid braking device and means preferentially responsive to pivotal movements of the truck mechanically connecting said liquid braking device with both the truck and the car body.

5. In a high speed rail car including a car body and bogie trucks supporting said car body and mounted to swivel pivotally upon a center pin and to swing laterally relative to said car body, mechanism for damping the pivotal vibrations 0! the trucks comprising a liquid braking device and means preferentially responsive to pivotal movements of the truck mechanically connecting said liquid braking device with both the truck and the car body and including preloaded yielding members adapted to limit the maximum damping force.

. FRANZ KRUCKENBERG.

' CURT B'I'EDEFELD.

WILLY BLACK. 

